Ford Focus Central Locking Problem

[RP66]

My son has a Ford Focus [2005].

Problem has arisen with the central locking.
Using his ignition key only the drivers door is unlocked all others are still locked, he can open the rear door on the drivers side from the inside but the other two doors remain firmly locked.

He has checked the fuses but they are Ok.

Anyone had a similar problem and what is the solution, or any ideas how to solve this.

Thanks.

 

[Dave54]

I remembered this thread from a week or two back.
//www.diynot.com/diy/threads/central-locking.417510/
The advice there is certainly worth following up on I'd have thought.